“Forging” refers to the working and/or shaping of a solid-state material by plastic deformation. Forging is distinguishable from the other primary classifications of solid-state material forming operations, i.e., machining (shaping of a workpiece by cutting, grinding, or otherwise removing material from the workpiece) and casting (molding liquid material that solidifies to retain the shape of a mold). “Forgeability” is the relative capacity of a material to plastically deform without failure. Forgeability depends on a number of factors including, for example, forging conditions (e.g., workpiece temperature, die temperature, and deformation rate) and material characteristics (e.g., composition, microstructure, and surface structure). Another factor that affects the forgeability of a given workpiece is the tribology of the interacting die surfaces and workpiece surfaces. The interaction between die surfaces and workpiece surfaces in a forging operation involves heat transfer, friction, and wear. As such, thermal insulation and/or lubrication between a workpiece and forging dies can influence forgeability.
Various alloys may be characterized as being “crack sensitive”. Ingots and other workpieces composed of crack sensitive alloys may form cracks along their surfaces and/or edges during forging operations or internally if material at the surface and interior move at different rates. Forming articles from crack sensitive alloys may be problematic because, for example, cracks formed during forging or other hot working operations may need to be removed from the worked article, which increases production time and expense, while reducing yield.
It is known in the art to decrease friction during forging operations by using lubricants. Inadequate or inconsistent forging lubrication can result in non-uniform plastic deformation of the workpiece, which is generally undesirable. For example, non-uniform plastic deformation can result in “barreling” of the workpiece and/or the formation of voids in the workpiece during forging operations. However, prior forging lubricants may have various deficiencies that result in a sub-standard forged article.
Given the drawbacks of current forging techniques, it would be advantageous to provide a more efficient and/or more cost-effective method of forging alloys, especially crack sensitive alloys. Additionally, it would be advantageous to decrease the friction between dies and workpieces during forging operations. More generally, it would be advantageous to provide an improved method for forging alloy ingots and other alloy workpieces.